Reverb time (RT60) calculator
Estimate how echoey a room is from its size and surfaces, and how much treatment it would take to fix it.
Estimated RT60 (mid frequencies)
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Target for this use
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Panels to reach the target
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How it works
RT60 = 0.161 × V ÷ A (metric: m³ and m²)
RT60 = 0.049 × V ÷ A (imperial: ft³ and ft²)
A = Σ (surface area × absorption coefficient)
RT60 = 0.049 × V ÷ A (imperial: ft³ and ft²)
A = Σ (surface area × absorption coefficient)
RT60 is the time it takes sound to fall by 60 dB after it stops. Wallace Sabine's formula estimates it from the room's volume and the total absorption of its surfaces. The calculator uses typical mid-frequency (around 500 Hz) absorption coefficients for each surface type.
Typical absorption coefficients used
| Surface | Coefficient (≈500 Hz) |
|---|
Published coefficients vary by product and frequency. These are representative values for a first estimate.
Targets
| Room use | Target RT60 |
|---|
Rule-of-thumb mid-frequency targets for small to medium rooms. Larger rooms and music spaces run longer.
Field notes
- Sabine is an estimate. It's most reliable in fairly live rooms with absorption spread around. Very dead rooms, or rooms with all the absorption on one surface, behave differently. Measure the real room with REW or similar when it matters.
- People absorb sound. A full room is noticeably drier than an empty one, which matters most for worship spaces and auditoriums.
- Low frequencies take more. Thin panels and ceiling tile work in the speech range but do little for bass. Rooms that sound fine for speech can still boom.
- For video meetings, shorter is better. Reverb makes echo cancelling harder and makes the room sound distant to the far end. See the echo troubleshooting guide.